This is a Phase II, single-center (Cleveland Clinic), two-arm, randomized, parallel-group superiority trial. The two arms will compare IOUS-guided margin selection against standard macroscopic margin selection in patients undergoing ileocolic resection for terminal ileal Crohn's disease. Patients and outcome assessors (pathologists, endoscopists) will be blinded to the intervention arm, while surgeons, by the nature of the intervention, cannot be blinded. Randomization will be computer-generated with concealed allocation using permuted blocks to ensure balanced group sizes.

Inclusion Criteria:

• Adults aged ≥18 years.
• Diagnosis of terminal ileal Crohn's disease with inflammatory or fibrostenotic phenotype localized to terminal ileum/ileocecal region and assessed on either preoperative imaging or during surgical exploration at the time of surgery.
• Scheduled to undergo primary ileocolic resection.

Exclusion Criteria:

• Penetrating disease with abscess or complex fistula requiring complex resection.
• Prior ileocolic resection.
• Diagnosis of Crohn's colitis.
• Pregnancy or inability to provide informed consent.
• Stoma at or before randomization: Participants in whom a stoma is required before randomization (identified intra-operatively) will not be randomized and will be excluded from the trial. Stoma after randomization: If a stoma is created after randomization-either during the index operation or at re-operation for postoperative complications-the participant remains in the trial. All feasibility, histopathology, operative, and safety outcomes will be collected and analyzed in the assigned arm (ITT). However, these participants will not be evaluable for the endoscopic-recurrence endpoint; they will be listed as "not assessed for endoscopic recurrence (stoma)" with reasons documented.
• Contraindication to IOUS (as determined by the surgeon).

Individual participant data will not be shared outside the Cleveland Clinic study team. Results will be reported in aggregate form in presentations and publications. This is a small single-center feasibility study, and the consent form does not include a plan for external sharing of de-identified individual participant-level data.